first marinate the fish with chilly powder ,turmeric powder, salt ,tamarind water .

.then keep it for half an hour.

then slightly fry it ,no need of deep fry, its to just get cooked .

then wipe off excess oil.

then heat the same pan with same oil and you can add more if you need

then add the onion , green chilly, garlic, ginger and tomato and sauté it well

when it gets brawn add the powders to it.

then stir for 1 or 2 mint and then add a cup of water ton it and when it gets boiled add the fried fish to it.

then mix it carefully without disturbing the fish.and close the pan for about 10 to 15 mint in low flame.

then the roast is ready and we can take this along with rice ,chapathy